Turbochargers are very delicate things. They spin at over 100,000rpm and operate to incredibly tight tolerances, so have the potential for catastrophic failure.
That said, a well-maintained and healthy turbocharger should be able to last the life of the engine without any troubles.
Here’s a list of the top five reasons a turbocharger fails, and, more importantly, how you can prevent them from destroying your turbo!
01 Oil Contamination
Oil contamination is the biggest killer of turbochargers. Irregular oil changes can cause carbon deposits to form in the oil, these then block the tiny oil ways in the turbocharger and starve it of sufficient lubrication.
The best way to prevent oil contamination is regular servicing and frequent oil changes and the specified service intervals.
Good quality oil of the correct grade for the application is a must too, as is cleanliness when any work is carried out to the engine.
02 Failed exhaust turbine
When the exhaust gases get too hot, as a result of poor engine setup/running, the turbine shaft in the turbo can get so hot it either melts or the turbine wheels can come completely away from the shaft!
The only way to avoid this, and other serious engine failures, is to make sure the engine is running correctly at all times.
03 Impact damage to compressor wheel
With such tight tolerances inside the turbo, and the compressor wheel spinning at over 100,000rpm, any foreign object that is allowed to enter the turbo can cause total destruction in seconds.
Even a small piece of debris hitting the compressor wheel will knock things out of balance – and an out of balance turbo only has seconds to live!
The only route into the compressor wheel is via the air filter, so make sure the air filter is doing its job properly and not allowing any dirt or debris to pass it.
04 Hot Stop
This is another surprisingly common cause for turbo failure, especially on performance cars.
After use the turbo will be exceptionally hot, and if you then shut the engine off the turbo will stop spinning and the turbine shaft will come to rest in one spot while it is still very hot.
This can cause to the turbine shaft to bend slightly, and then the whole turbo is out of balance.
The cure to ‘hot stop’ issues s very simple; don’t turn the engine off when it’s hot. Allow the engine to idle so the turbo can cool with oil still flowing through it and only shut if off when everything has cooled down sufficiently.
A gentle drive for the last 5 minutes before you reach your destination serves the same purpose, allowing you to turn the engine off as soon as you stop.
05 Wastegate arm bending
This problem only affects internal-wastegate turbos, (many Variable Nozzle Turbochargers as used on modern diesel engines don’t require the use of a wastegate) but is surprisingly common.
After repeated heat cycles, the wastegate arm can actually bend, causing the penny washer to lift away from the wastegate hole it’s supposed to cover.
This allows the exhaust gases to escape from the turbocharger even when the wastegate is fully shut, resulting in slow spool up and poor engine performance.
The main culprit is excessive heat fatiguing the wastegate arm, so ensure the engine is running correctly and in good overall health to prevent the exhaust gas temperatures rising too high.